* Added applier side TOI commit order enter and leave

* Added cleanup_transaction() method to client_service in order to
  provide a way to make DBMS side cleanup when transaction
  is cleaned up

test/mock_client_state.hpp

@@ -122,6 +122,7 @@ namespace wsrep
             return client_state_.append_data(data);
         }
 
+        void cleanup_transaction() WSREP_OVERRIDE { }
         size_t bytes_generated() const
         {
             return bytes_generated_;